单项选择题
In comparison to electric power，hydraulic power for jacking systems has the advantage of（）.
A.better control capabilities B.less maintenance and repair C.fewer personnel needed during jacking D.less preload needed
单项选择题 I’ll have the damaged parts repaired in Hongkong and send you in due course the amount of expenses（）.
单项选择题 If your radiotelephone fails while underway,（）.
单项选择题 If your bridge-to-bridge radiotelephone ceases to operate，you must（）.
